Process for modifying aromatic hydrocarbons



April 10, 1945. F. E. FREY ETAL PROCESS FOR MODIFYING AROMATICHYDROCARBONS Filed Aug. 22, 1936 if gig I) Y \1 [1* (I w INVENTOR.FREDERICK E. FREY BY JEAN P. JONES 1 cm on? ATTORNEYS.

yiile, Okla,

a rat read Domny, a corpretlon oi Delaware Application august 22, 1936,Serial No. 97AM i Cia.

This invention relates to-the iotion oi allsyl derivatives from aromatichydrocarbons, and particularly to the formation from aromatichydrocarbons of derivatives containing one or more alkyl groups morethan are contained in the'original aromatic hydrocarbons, andfurthermore particularly to the formation of these derivatives by thepyrolytlc treatment of a mixture comprising an aromatic hydrocarbon andan aliphatic hydrocarbon under the influence of'superatmos- .phericpressure in-the absence'of any catalytic material other than that whichincidentally may .be presented by the walls of the reaction vessel orfortuitous impurities.

It has been known for some time how to pre-' pare alkylated aromatichydrocarbons, that is.

. attach ethyl, propyl, and other alkyl groups to the aromatic moleculesby employing some catalytic means or condensing agents. These areillustrated-by the well known synthesis of Frledel and Crafts, in whichan 'alkyl halide is caused to alkylate an aromatic molecule by the aidof aluminum chloride,by the reaction of an olefin and arr-aromatichydrocarbon in the presence of some condensation agent such asphosphoric acid or aluminum chloride and-by other similar means.

' Aromatic hydrocarbons suchas benzene, naphthalene and others areproduced in relative abundance in coal carbonization, in the enrichmentof manufactured gas by the cracking of petroleum, and in gas reformingor pyrolysis. Relatively less amounts of alkylated derivatives such astoluene, xylene, ethyl benzene, alkylnaphthalenes are formed whichdiffer somewhat from the purely cyclic aromatics in properties and havefound a variety of: special uses.

An-oblect of our invention is to produce alkyl derivatives from aromatichydrocarbons such as toluene, ethyl benzene and xylene from benzenethecorresponding derivatives, from naphthalene,

and to introduce alkyl groups into other aromatic hydrocarbons which mayalready contain one or more alkyl groups. Another object is theconcomitant productionof more or less of condensa- 1 tion products ofaromatic hydrocarbons formed-by union of two molecules with elision ofhydrogen.

' Alkyl groups of varying molecular weight may be introduced, such asmethyl, ethyl, etc.

We are aware that in the course of the ordinary uncatalyzed pyrolysis ofcrude non-aromatic hy-' drocarbons, materials containing more or less'ofalkyl aromatics may be formed under suitable conditions, and that thethermal treatment of benzene mired with ethylene produces styreneaccompanied by other products. We have discovered that a high yield 02:1'12

companied by relatively slight amounts of contaminating by-products, canbe produced by heating at an elevated pressure the aromatic hydrocarbon,into which it is desired to introduce alkyl substituents, with aliphatichydrocarbons. The temperature required is in the neighborhood of that atwhich the aliphatic hydrocarbons tend to crack or polymerize, and isreadily determined by experiment. The aliphatic hydrocarbons may rangeall the way from methane to paraffln wax or paramn oil in molecularweight, and may be of either saturated orunsaturated type. Low molecularweight hydrocarbons, normally gaseous, are usually preferable sincetheir use minimizes the formation of by-product hydrocarbons, throughsplitting and polymerization, which boil in the range of the desiredalkylated aromatics and may constitute undesired impurities. When simpleparamns are employed, more or less decomposition takes place duringreaction, but the formation of polymeric compounds is not extensive andlarge proportions of these hydrocarbons, admixed with the aromatichydrocarbon may be used, since the relatively low boiling temperaturemakes their separation from alwlation products easily accomplished. Thesimple olefins may likethroughout the reaction period may be desirableto reduce the tendency to polymerize which high momentary concentrationswill encourage. The quantity of aliphatic hydrocarbons then may varyfrom 5 per cent or less to quantities such that they predominate in thereaction mixture, and by a substantial proportion of aliphatichydrocarbons in admixture with aromatic hydrocarbons will be understoodto be as explainedand defined in the foregoing discussion. Hydrogen maybe added to the reaction mixture to inhibit condensation reactions'ofaromatics and this is also a part of our invention.

The proportion may vary widely; as little as 5 mol per cent may beadequate at high pressures and when thermally treating non-oleflnichydrocarbon mixtures, while when oleflns are employed as the alkylatingagent hydrogen will be consumed by hydrogenation of olefins and toobtain maximum inhibitingv of aromatic to aromatic union, over 50 molper cent of hydrogen may be required. By a substantial proportion ofhydrogen will be understood its addition as the foregoing discussiondirects.

An initial mixture of aromatic and aliphatic hydrocarbons-iscontinuously introduced into a reaction zoneunder a pressure in excessof 250 pounds per square inch, and preferably between 1,000 and 5,000pounds per square inch, at a temperature determined by experiment andusually of 400 to 800 C., and is held in this reaction zone for a periodof time readily determined by trial but brdinarily not less than 0.5minute nor more than minutes, the resulting mixture being removed fromthe reaction zone and the desired derivatives separated therefrom.

We have found that extensive reaction, wherein the aromatic hydrocarbonsare more or less completely converted in a single thermal treatment, maylead to excessive formation of heavy condensation products, andconsequentl it is usually desirable to interrupt the reaction while 50per cent or even more of the original aromatic hydrocarbons remainunreacted. Such unreacted hydrocarbons may be separated from theeffluents to be subjected once more to thermal alkyiating conversion. Insome cases polynuclear condensation compounds, which form at the expenseof the alkyl derivatives, are not desired. If hydrogen is addedas-previously set forth to the mixture of aromatic and aliphatichydrocarbons to be subjected to reaction, the formation of condensationcompounds is inhibited, while alkylation proceeds readily.

Unreacted components may be reintroduced into the heating and reactingzones. Undesirable polynuclear aromatic hydrocarbons formed may bereintroduced into the heating and reacting zones for dissociation, orthey may be separately reacted in the presence of hydrogen andreintroduced into the system as will be described and shown. Thetemperature of the reaction zone will vary in an inverse relationshipwith the pressure to which the reactants are subjected. Actualconditions of operation will vary somewhat with variation in the initialaromatic and aliphatic materials and upon the products desired, and maybe readily determined by experiment. Upper limits of temperature orpressure will be dependent also upon the materials used in theapparatus.

An example of our invention is as follows:

A mixture comprising 88.9 per cent by weight of benzene and 11.1 percent by weight of ethane was continuously passed through a reaction zoneheated to 605 C. and at a pressure of 2865 pounds per square inch. Themixture was subjected to this temperature for a period of about 2minutes, immediately cooled and withdrawn. There was produced ethylbenzene and toluene, in the ratio of approximately 5.5:1 along withtraces of unsaturated materials and some polynuclear aromatic compounds.In a similar experiment, the reaction was allowed to proceed in thepresence of hydrogen, which decreased the formation of polynucleararomatic hydrocarbons to the ultimate benefit of the formation of thealkylated products of about the same composition.

As a further example of this invention a mixture comprising 91.8 percent by weight of naphthalene and 8.2 per cent by weight of ethane maybe passed continuously through areaction zone heated to 600 C. under apressure: of 2900 pounds per square inch, being subjected to thistemperature for a period of about 2 minutes, then immediately cooled andwithdrawn. The product will contain a fraction comprising a mixture ofmethasvasos yl naphthalene and a" considerably larger amount of ethylnaphthalene along with small amounts of unsaturated compounds andheavier polynuclear compounds.

A further and more complete operation of our process will now bepresented with reference to entering the fra'ctionator 2|. stood thatheat from some other, or extraneous the accompanying drawing, wherein:

The figure illustrates diagrammatically one type of apparatus forpracticing the present invention.

Aromatic hydrocarbons, such as benzene, are maintained under suitablepressure and introduced through pipe i0 and mixed therein with suitablealiphatic material, which may be ethane and which is introduced throughpipe II. The mixture of aromatic and aliphatic hydrocarbons iscompressed by the pump l2 in pipe ill to a suitable pressure inexcess-of 250 pounds per square inch, and preferably to a pressurebetween 1,000 and 4,000 pounds per square inch. If desired, hydrogen maybe introduced by way of pipe I! and added to the mixture of hydrocarbonsin pipe l0, and the induction thereof may be controlled by valves l4 andIll, and any necessary or desired compression of the hydrogen may beeffected by pump 16.

The mixture of aromatic and aliphatic hydrocarbons plus the addedhydrogen then passes through pipe l0 into and through the reaction coilsH, which are suitably housed in the furnace I, wherein it is heated tosome temperature in excess of 400 C. and held at that temperature for aperiod of time in excess of 0.5 minute. The resultant products oreiliuents then pass from the reaction coils I! through the pipe i9 andthe expansion valve 20 and into the fractionator )2]. If desired a partor all of the eiliuents from reaction coil I! may be passed through pipe22 and into coil 23, located in the kettle of the fractionator 2i, inorder to utilize some of the sensible heat of the eiliuents. From coil23 the eilluents pass through pipe 2 and again re-enter pipe i! and flowinto the fractionator. To provide for such a utilization of the sensibleheat of the effiuents valve 25 is provided in pipe is adjacent thefractionator, and valve 26 is provided in pipe 22. By manipulation ofthese valves all or any part of the eiiluents flowing through pipe [8may be caused to circulate through the coils 23 before It is to beundersource, other than the sensible heat of the eilluents may besupplied to heat the kettle contents.

contains the desired alkylated products along with other heaviermaterial which may be formed. .These kettle products are removed fromthe fractionator 2| by way of pipe 21 and are passed to a system ofrectifying units designated by the reference numeral 28, wherein aseparation is made between the desired allrylated product or controlledby the valve 52.

i'radtionator kettle 02 if desired.

' Fractionator, or separator, 32 operates at some superatmosphericpressure, but at a pressure less than the operating pressure offractionator 2i, and preferably in the neighborhood of 300- pounds persquare inch; Within the iractionator; or separator, 82 separation ismade between fixed s, which may include methane and hydrogen, andheavier material which is withdrawn by way of pipe ill} and passed baclrthrough pipe 39,

valve t0, and pipe 01 to be introduced into pipe i0. Or, in lieu ofpassing the heavier material back for introduction into pipe asdescribed. they may be withdrawn through the pipe t2 controlled by valve63.

A cooling coil 00 may be interposed in the top of the fractionator, orseparator, 02 and additional cooling means such as that diagrammaticallydesignated by the reference numeral 00 may also be provided if desired,so that the gases leav ing the fractionator orseparator by way of pipe06, will if desired, be freedfrom substantially all of the hydrocarbonscontaining two or more carbon atoms. To aid in stripping these gases ofthe more volatile of the last mentioned hydrocarbons, an absorbingliquid which may be either an aliphatic or aromatic oil is introducedthrough line 01? and valve 08- into the fractionator, or

separator, 32, and which oil will eventually be withdrawn therefromalong with the kettle products.

Moderate cooling means may be used in fractionator, or separator; 32 sothat only asmall 1 part oi the ,lightertmaterial need be treated in"-cooler d5.

Fixed gases leaving fractionator, or separator, 32 and cooler 65 may berecycled back through pipe 09 and valve 50 for further treatment in theprocess, and introduced into pipe it, or in lieu thereof any part or-allof these gases may be withdrawn from the process through pipe bi Howeverit is to be understood that-the gases which pass through pipe 0! may betreated in apparatus not illustrated, and a hydrogen rich mixtureresulting therefrom may be introduced into theprocess through pipe i3.

Polynuclear aromatic material, either alone at elevated temperatures orin solution with hydrocarbon material, is withdrawn from the rectityingunits 28 through pipes 53 and t and valve 55, and forced by pump 06through the remainder of pipe 50 and through valve 5? andzinto thereaction coils 58 which are'housed in the-furnace 59.

Hydrogen from any suitable source, such. as from line it may bepassed'through pipe 60 and valve 8! and compressed by pump 62 and-forcedthrough the remainder of pipe 00 and through" valve 63 and introducedintopipe 5d. The re- .sultant mixture in pipe 50, which will includepolynuclear aromatic material together with hydrogen then passes at apressure in excess of 250 iii 00, which coils are heated to sometemperature in excess of 400 C. The mixture is exposed in the reactioncoils for a period of time which may be greater than 0.0 minute, butless than minutes. By this thermal treatment of the mixture ofpolynuclear material and hydrogen dissociation into simpler aromatics iseffected.

Actual pressure, temperature and exposure times will be dependent uponthe nature of the polynuclear material to be treated, and may readily beexperimentally determined.

The eiiiuents from the reaction coils 50 pass through pipe 0t and valve00, and expansion valve 00 and into the pipe it. If necessary, or

desired, additionaal pressure may be applied to the eii'iuents. leavingthe reaction coils by closing valve 0% in pipe t0 and by passing theeilluents' through pipe ti, valve 00, pump 00, pipe i0 and valve 'ii,and thence back into pipe 00.

It is to be understood that any part or all of the efliuents flowingthrough pipe 0t may be diverted therefrom by manipulation of valve. 00

and caused to flow through pipe i2 and valve l3 into pipe 239.Furthermore, if desired, all or any part of the untreated polynucleararomatic hydrocarbons flowing through pipe 00 may be di rectlyintroduced into pipe ii, and subsequently into pipe ill. by way of pipeit in when is interposed the valve 75, without adding hydrogen to theuntreated polynuclear aromatic hydrocarhops and also without passingthem through the reaction coils b8. Although preferred methods ofoperating the process have been given, many variations in procedure orin the material processed will be apparent which may be made withoutdeparting from the spirit of the invention. The invention is not to beconstrued as being'limited by such described procedure as herein taughtnor by the examples given, but is to be limited only as set forth in theaccompanying claims forming a part of this specification.

What we claim and desire to secure by Letters Patent is: V

l. A process for converting aromatic hydrocarbons into alkyl substitutedderivatives, which comprises subjecting aromatic hydrocarbons to v whichhas been added a substantial proportion of at least 250 pounds persquare inch to; form alkyl substituted derivatives, then separating fromthe thermally treated hydrocarbons the alkyl substituted derivatives soproduced.

2. A process for converting benzene into alkyl substituted derivatives,which comprises subject ing benzene to which has been added asubstantial proportion of aliphatic hydrocarbons and also a substantialproportion of hydrogen to a reaction temperature of 400 to 800 C. whilemaintaining a pressure of at least 250 pounds per square inch to'formalkyl substituted derivatives, then separating from the thermallytreated hydrocarbons the alkyl substituted derivatives so produced.

3. A-process for converting naphthaleneinto alkyl substitutedderivatives, which comprises subjecting naphthalene to which hasbeen-added a substantial proportion of aliphatic hydrocarhens and also asubstantial proportion of hydrogen to-areaction temperature of 400to'800 C. while maintaining a pressure ofat least 250 pounds per squareinch to form alkyl substituted derivatives, then separating fromthethermally 4 tail:

treated hydrocarbons the alkyl substituted deri atives so produced.

4. A process for converting aromatic hydrocarbons into alkyl substitutedderivatives, which comprises subjecting the said aromatic hydrocarbonsto which has been added a substantial proportion of aliphatichydrocarbons to a reaction temperature of 400 to 800 C. whilemaintaining a pressure oi at least 250 pounds per square inch to producealkyl substituted derivatives, separating from the thermally treatedhydrocarbon the alkyl substituted hydrocarbons so produced, separatingalso therefrom the unconverted aromatic hydrocarbons and subjecting thelast mentioned hydrocarbon to the aforesaid reaction, and separatingalso therefrom the polynuclear aromatic hydrocarbons formed in theaforesaid reaction, subjecting these last mentioned p lynuclear aromatichydrocarbons in admixture with a substantial proportion of hydrogen to areaction temperature 01' 400 to 800 C. while maintaining a pressure ofat least 250 pounds per square inch to produce simpler non-alkylatedaromatic hydrocarbons. and introducing at least a portion of theeilluent oi the last said treatment into the cycle of the firstmentioned reaction.

5. A pyrolytic process for converting aromatic hydrocarbons into alkylsubstituted derivatives, which comprises subjecting aromatichydrocarbons to which has been added a substantial proportion ofsaturated aliphatic hydrocarbons to a reaction temperature between 400and 800 C. in the absence of a catalyst for a period of time such thatat least 50 per cent of the initial aromatic material remains unreactedwhile maintaining a pressure in excess of 250 pounds per square inchwhereby alkyl substituted derivatives of said aromatic hydrocarbons areformed and separating from the products said alkyl substitutedderivatives.

. 6. A pyrolytic process for reacting paramn hydrocarbons and aromatichydrocarbons to form alkyl substituted derivatives of said aromatichydrocarbons, which comprises subjecting in a reaction zone an aromatichydrocarbon material with which has been dispersed a substantialproportion of a paraflin hydrocarbon of not less than two nor more thanfive carbon atoms per molecule to a reaction temperature of 400 to 800C. in the absence of a catalyst while maintaining a pressure of at least250 pounds per square inch and for a period of time of at least 0.5minute and such that at least about 50 per cent of said aromaticmaterial remains unreacted and adapted to produce alkyl substitutedderivatives or aromatic hydrocarbons from said aromatics and saidparaifins, and separating from the reaction, effluent a hydrocarbonfraction containing alkyl substituted aromatic derivatives so produced.

7. A process according to claim 5 in which the aromatic hydrocarboncomprise benzene and in which the saturated aliphatic hydrocarbonscontain not less than two nor more than five carbon atoms per molecule.

8. A pyrolytic process for converting aromatic hydrocarbons into alkylsubstituted derivatives,

which comprises heating under a pressure in excess of 250 pound persquare inch a stream of aromatic hydrocarbons in which a substantialproportion of aliphatic hydrocarbons and a substantial proportion ofhydrogen are dispersed to a reaction temperature between 400 and 800 C.for a period of time such that at least 50 per cent of said aromatichydrocarbons rema n unreacted whereby alkyl substituted derivatives ofsaid aromatic hydrocarbons are formed and subsequently removing from thestream a fraction containing said derivatives.

9. A continuous pyrolytic process tor iormins alkyl derivatives ofaromatic hydrocarbons. which comprises subjecting aromatic hydrocarbons,with which have been dispersed substantial proportion of saturatedaliphatic hydrocarbon and also a substantial proportion of hydrogen, toa reaction temperature between 400 and 800 C. while maintaining apressure on the reaction mixture 01' at least about 250 pounds persquare inch forming alkyl substituted derivatives or said aromatichydrocarbons and polynuclear aromatic hydrocarbons. separating from thereaction mixture a fraction containing alkyl substituted hydrocarbons soproduced, separating also a traction containing unreacied aromatichydrocarbons and said polynuclear aromatic hydrocarbons and returninssaid fraction to be mixed with aromatic hydrocarbons charged to theprocess.

10. A multistep process for converting aromatic hydrocarbons into aikylsubstituted derivatives, which comprises dispersing in a stream ofaromatic hydrocarbons a substantial proportion of saturated aliphatichydrocarbons and submitting the mixture in a first step to a reactiontemperature between about 400 and 800 C. in the absence of a catalystwhile maintaining a pressure of at least 250 pounds per square inchformins alkyl substituted derivatives of aromatic hydrocarbons andpolynuclear aromatic hydrocarbons. separating from the eiliuent 01' saidstep a fraction containing alkyl substituted aromatic hydrocarbons soproduced, separating also therefrom unreacted aromatic hydrocarbons andintroducing said hydrocarbons to the first said step, and separatingalso polynuclear aromatic hydrocarbons formed in said first step,subjecting said polynuclear aromatic hydrocarbons in admixture with asubstantial proportion oi. hydrogen in a second step to a reactiontemperature between 400 to 800 C. while maintaining a pressure of atleast 250 pounds per square inch whereby simpler aromatic hydrocarbonsare produced, and passing the effluent of said second step into thecycle of the first mentioned step.

11. A process for converting aromatic hydrocarbons into alkylsubstituted derivatives, which comprises subjecting an aromatichydrocarbon material with which has been dispersed a substantialproportion of aliphatic hydrocarbons and also a substantial proportionof hydrogen to a reaction temperature between 400 and 800 C. for aperiod between 0.5 and 15 minutes in the absence of a catalyst and undera pressure between 250 and 5000 lb./sq. in. to form alkyl substitutedderivatives of said aromatic hydrocarbon material, and separating fromthe eflluent alkyl substituted derivatives so formed. 1

12. The process of claim 11 wherein the said aliphatic hydrocarbonscomprise substantially a paramn hydrocarbon of not les than two and notmor than five carbon atoms per molecule.

13. The process of claim 11 wherein the said aliphatic hydrocarbonscomprise an olefin hydrocarbon of not more than five carbon atoms permolecule.

14. A process for converting aromatic hydrocomprises subjecting in afirst reaction zone an aromatic hydrocarbon material with which hasbeendispersed a substantial proportion oi al phatic hydrocarbons to areaction temperature of 400 to 800 C. in the absence of a catalyst whilemaintaining a pressure of at least 250 pounds per square inch to producealkyl substituted derivatives, passing the efliuent of said firstreaction zone to separating means, separating from the thermally treatedhydrocarbons the alkyl substituted hydrocarbons so produced, separatingalso therefrom aromatic hydrocarbons corresponding to said aromatichydrocarbon material and returning the same to said first reaction zone,and separating also polynuclear aromatic hydrocarbons formed in theaforesaid reaction, subjecting these last mentioned polynuclear aromatichydrocarbons in admixture with a substantial propor-

